Donald Trump's presidential aspirations may have just become bad for his business.

N.Y.C.-based gay activist Allen Roskoff, who co-authored the nation's first gay rights bill in the 1970s, is so taken aback by Trump's comments to the Des Moines Register about his anti-gay marriage and equality stance that he's calling for a boycott of the Donald's business interests.

"He's crossed the Rubicon," says Roskoff, a founder of the Jim Owles Liberal Democratic Club. "It's unconscionable that he could exist in New York City."

On Thursday, Trump talked about "exploring" a presidential run in an interview with the Register's Thomas Beaumont, who asked the "Celebrity Apprentice" host if he supports "allowing same-sex couples to marry."

Trump said "no," but didn't stop there. When Beaumont asked whether gay couples should have access to "the same benefits as married couples," the mogul initially replied that his attitude on the issue was not yet "fully formed."

After thinking about it for a moment, however, Trump said: "As of this moment, I would say no and no" to gay marriage and civil benefits.

That answer may have resonated with Iowa conservatives who overwhelmingly opposed the Iowa Supreme Court's 2009 decision to overturn the state's gay marriage ban.

But in New York, home to one of the largest gay and lesbian communities in the U.S., Trump's comments may end up biting him in the ass-ets.

"He's an extreme bigot," says Roskoff, who was the first openly gay appointed official in New York City and has served under Gov. Mario Cuomo and Mayor David Dinkins, among others."

Roskoff adds: "Not only should gays be furious, we should be boycotting the products of the advertisers on his TV show"—"Celebrity Apprentice," which premiered Sunday night on NBC-TV "and certainly boycotting his casinos and hotels and apartment buildings."

Noting that Trump recently switched his stance on abortion from pro-choice to pro-life, Roskoff says: "His game plan is to appeal to the extreme right." But he continues: "How he does business in New York, how he's tolerated is beyond me. I think things are going to change for him."

Trump's comments are also interesting in light of the fact that in January his daughter Ivanka Trump reportedly attended the New York City Reception in Support of Freedom to Marry, an organization that's seeking marriage equality nationwide for same-sex couples.

Trump was traveling Sunday and could not be reached for comment. Through a spokesman, he said only: "I'm opposed to gay marriage."